1. Field of the Invention
The present invention relates to a hood, and more particularly to a hood for a digital image-collecting lens.
2. Description of Related Art
A conventional hood for a digital image-collecting lens in accordance with the prior art shown in FIG. 7 comprises base member (50) adapted to cover an image sensor (70) and a lens seat (60) longitudinally mounted to the base member (50).
The base member (50) includes a recess (51) defined in a bottom of the base member (50) for receiving the image sensor (70). A protrusion (52) extending from a top surface of the base member (50) and a threaded hole (53) is longitudinally defined in the protrusion (52). The threaded hole (53) extending through the protrusion (52) and communicates with the recess (51). The threaded hole (53) straightly corresponds to a center of the image sensor (70). The base member (50) includes two opposite sides each having an ear (54) laterally extending from the base member (50). A through hole (541) is longitudinally defined in each of the ear (54) such that the base member (50) can be easily secured on a printed circuit board by bolts (not shown) extending through the through hole (541) and screwed into the PCB.
The lens seat (60) is cylindrical and has a threaded section (61) formed near a lower section. The threaded section (61) is screwed into the threaded hole (53) to securely mount the lens seat (60) on the base member (50). The lens seat (60) has a hole (62) centrally and longitudinally defined therein for receiving a camera lens (80) of the digital image-collecting lens.
With reference to FIG. 8, as usual the camera lens (80) projects a developing zone (800) including a preferred area (801) centrally situated in the developing zone (800) and an aberration area (802) surrounding the preferred area (801). For a good image effect, a coupling crystal (71) of the image sensor (70) must be situated within the preferred area (801). However, the lens seat (60) is cylindrical because the hole (62) is longitudinally defined in the lens seat (60). With reference to FIGS. 9 and 10, the camera lens (80) may be extruded and slanting due to the following causes:
1. The thread of the lens seat (60) or threaded hole (53) in the base member (50) becomes deformed.
2. The threads of the lens seat (60) and threaded hole (53) in the base member are spiraled too tight.
3. The threaded section (61) becomes deformed.
As described above, an axis of the camera lens (80) is inclined relative to that of the coupling crystal (71) such that the coupling crystal (71) may be partially located in the aberration area (802). Consequently, the contours of the object in the image may be partially blurred. Furthermore, the image may be fully blurred when the axis of the camera lens (80) is seriously inclined relative to that of the coupling crystal (71) and the focus of the camera lens (80) does not focus on the coupling crystal (71).
With reference to FIG. 11 that shows another connecting type of the base member (50) and the lens seat (60). As shown in FIG. 11, the lens seat (60) is tightly inserted into the base member (50). As well known, the base member (50) and the lens seat (60) are manufactured of plastic by injecting molding for reducing the manufacturing cost such that the preciseness of the base member (50) or the lens seat (60) is difficult to accurately be controlled. Consequently, the lens seat (60) is easily and inward radially compressed after being inserted into the base member (50) such that the camera lens (80) easily causes the above problems. Furthermore, the base member (50) and the lens seat (60) expand when the temperature of the environment becomes high. This appearance may cause an inward radially force that equally acts on an outer periphery of the lens seat (60). Consequently, the curvature of the camera lens (80) may be changed and the collected image becomes blurred.
The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional hood for a digital image-collecting lens.
The main objective of the present invention is to provide an improved hood for a digital image-collecting lens.
To achieve the objective, the hood in accordance with the present invention comprises a hood for a digital image-collecting lens including a base member that has a recess defined in a bottom of the base member to receive an image sensor that has a coupling crystal contained in the image sensor. A through hole is defined in the base member and communicating with the recess and longitudinally and straightly aligns with the coupling crystal. A lens seat is longitudinally and secured in the through hole in the base member and includes a through hole longitudinally and centrally defined in the lens seat. The through hole in the lens seat receives a camera lens of the digital image-collecting lens. At least one annular slot is longitudinally defined between an inner periphery of the through hole in the lens seat and an outer periphery of the lens seat, and longitudinally extending to corresponds to the camera lens.